Add intergalactic-transmission exercise by kahgoh · Pull Request #2543 · exercism/problem-specifications

kahgoh · 2025-03-07T23:27:18Z

This is a proposal for a parity bit exercise.

I've created a proof of concept: exercism/csharp#2398

Note, I wasn't quite sure how best to represent byte data in the JSON. I've used an array of strings with the hex values as Visual Code was telling me "expected comma" if I didn't use the string.

BNAndras · 2025-03-07T23:28:54Z

+
+Your job is to help implement the message sequencer to add the parity bit to the messages and the decoder to receive messages.
+
+The entire message, itself, is sequence of a number of bytes.


Suggested change

The entire message, itself, is sequence of a number of bytes.

The message is a sequence of bytes.

BNAndras · 2025-03-07T23:30:59Z

+Your job is to help implement the message sequencer to add the parity bit to the messages and the decoder to receive messages.
+
+The entire message, itself, is sequence of a number of bytes.
+The transmitters and receivers can only transmit and receive one byte at a time, so parity bit needs to be added every eighth bit. 


Suggested change

The transmitters and receivers can only transmit and receive one byte at a time, so parity bit needs to be added every eighth bit.

The transmitters and receivers can only transmit and receive one byte at a time, so a parity bit needs to be added every eighth bit.

Also as a layperson, I’m already a bit confused by bit vs byte so we may want to simplify.

BNAndras · 2025-03-07T23:32:02Z

+The transmitters and receivers can only transmit and receive one byte at a time, so parity bit needs to be added every eighth bit. 
+The algorithm for adding the bits is as follows:
+1. Divide the message bits into groups of 7, starting from the left (the message is transmitted from left to right).
+2. If the last group has less than 7 bits, append some 0s to pad the group to 7 bits.


Suggested change

2. If the last group has less than 7 bits, append some 0s to pad the group to 7 bits.

2. If the last group has less than 7 bits, append 0s until that group has 7 bits.

What are the 0s signifying?

BNAndras · 2025-03-07T23:33:22Z

+1. Divide the message bits into groups of 7, starting from the left (the message is transmitted from left to right).
+2. If the last group has less than 7 bits, append some 0s to pad the group to 7 bits.
+3. For each group, determine if there are an odd or even number of 1s.
+4. If the group has even number of 1s or none at all, append a 0 to the group. Otherwise, append 1 if there is odd number.


Suggested change

4. If the group has even number of 1s or none at all, append a 0 to the group. Otherwise, append 1 if there is odd number.

4. If the group has an even number of 1s or none at all, append a 0 to the group. Otherwise, append 1 if there is an odd number of 1s.

BNAndras · 2025-03-07T23:34:05Z

+
+The first group contains two 1s (an even number of 1s), so 0 is appended to the group.
+The second group has none, so append 0.
+The rest have three, so they append 1.


Suggested change

The rest have three, so they append 1.

The rest have three each, so they append 1.

IsaacG · 2025-03-08T04:48:08Z

@@ -0,0 +1,37 @@
+# Instructions
+
+Your job is to help implement the message sequencer to add the parity bit to the messages and the decoder to receive messages.


The double "to" in this sentence might be worth changing.

IsaacG · 2025-03-08T04:49:56Z

+
+The first group contains two 1s (an even number of 1s), so 0 is appended to the group.
+The second group has none, so append 0.
+The rest have three, so they append 1.


Drop the "they". There is no "them" in the other steps.

IsaacG · 2025-03-08T04:50:16Z

+| C    0    | 0    0    | 7    1    | 1    B    | E    1    |  (in hex)
+```
+
+Thus, the transmission sequence is 0xC0_00_71_1B_E1.


Suggested change

Thus, the transmission sequence is 0xC0_00_71_1B_E1.

The resulting transmission sequence is `0xC0_00_71_1B_E1`.

…o exercise/intergalactic-transmission

kahgoh · 2025-04-04T14:36:00Z

Just pushed updates. Ended up re-writing the instructions.md while working through the comments though 😅.

ErikSchierboom

Just a couple of comments! Really looking forward to implementing this

ErikSchierboom · 2025-04-08T14:28:20Z

Looks good! Does anybody have time to test the canonical data by doing an implementation of this exercise?

IsaacG · 2025-04-08T16:34:21Z

Looks good! Does anybody have time to test the canonical data by doing an implementation of this exercise?

I could write a solution using the canonical data later today.

IsaacG · 2025-04-08T19:44:03Z

+          "input": {
+            "message": ["0x02"]
+          },
+          "expected": ["0x01", "0x00"]


0x02 is 0000 0010. Pad that to 7-bit chunks and you get 0000 001_ | 0000 000_. Add parity bits for 0000 0011 | 0000 0000. Shouldn't the output be 0x03 0x00?

You're right, it should be 0x03 0x00! I'll update the data.

» python intergalactic_transmission.py https://raw.githubusercontent.com/exercism/problem-specifications/eb8ef7696498709799f1ff6830189ab23c471d17/exercises/intergalactic-transmission/canonical-data.json {'pass': 26, 'fail': 0}

My solution says the data is correct :D Or, the data says my solution is correct.

IsaacG · 2025-04-08T19:58:00Z

Solution that uses the canonical_data.json as input: https://gist.github.com/IsaacG/0e628e51c39e44c4ebbc470b64c61675

The second case seems to have a bug. All the other test cases pass.

Co-authored-by: Anastasios Chatzialexiou <16361161+tasxatzial@users.noreply.github.com>

tasxatzial

Verified tests in Clojure and I wasn't able to spot any issues.

Add intergalactic-transmission exercise

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kahgoh requested a review from a team as a code owner March 7, 2025 23:27

BNAndras reviewed Mar 7, 2025

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kahgoh added 5 commits April 4, 2025 22:16

Revise instructions & introduction

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Merge branch 'main' of github.com:exercism/problem-specifications int…

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…o exercise/intergalactic-transmission

Fix formatting

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Use bullet list for task list

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Co-authored-by: Anastasios Chatzialexiou <16361161+tasxatzial@users.noreply.github.com>

Fix alignment

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Co-authored-by: Anastasios Chatzialexiou <16361161+tasxatzial@users.noreply.github.com>

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kahgoh merged commit 75e16b1 into exercism:main Apr 16, 2025
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kahgoh deleted the exercise/intergalactic-transmission branch April 18, 2025 08:37

kahgoh mentioned this pull request Apr 19, 2025

Add intergalactic-transmission exercise exercism/elixir#1566

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		Your job is to help implement the message sequencer to add the parity bit to the messages and the decoder to receive messages.

		The entire message, itself, is sequence of a number of bytes.

	The entire message, itself, is sequence of a number of bytes.
	The message is a sequence of bytes.

	The transmitters and receivers can only transmit and receive one byte at a time, so parity bit needs to be added every eighth bit.
	The transmitters and receivers can only transmit and receive one byte at a time, so a parity bit needs to be added every eighth bit.

	2. If the last group has less than 7 bits, append some 0s to pad the group to 7 bits.
	2. If the last group has less than 7 bits, append 0s until that group has 7 bits.

	4. If the group has even number of 1s or none at all, append a 0 to the group. Otherwise, append 1 if there is odd number.
	4. If the group has an even number of 1s or none at all, append a 0 to the group. Otherwise, append 1 if there is an odd number of 1s.

	The rest have three, so they append 1.
	The rest have three each, so they append 1.

		@@ -0,0 +1,37 @@
		# Instructions

		Your job is to help implement the message sequencer to add the parity bit to the messages and the decoder to receive messages.

	Thus, the transmission sequence is 0xC0_00_71_1B_E1.
	The resulting transmission sequence is `0xC0_00_71_1B_E1`.

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kahgoh commented Mar 7, 2025

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kahgoh commented Apr 4, 2025

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